Optical filters may be desirable for use in applications such as channelization of microwave signals in the optical domain, optical or microwave signal aliasing, and ultra-dense optical communications. However, optical filters are subject to drifting instability due to a drift in their center frequency. The drifting instability of the optical filter varies and may depend on the underlying filter technology and components involved. Nevertheless, Heisenberg's uncertainty principle teaches that, fundamentally, as the filter bandpass gets narrower, a higher probability of drifting is expected. Drifting instability is undesirable in many applications including the above mentioned applications.